Water Permeability Affected by Wettability Alteration:Interfacial Study of Increasing Injection Mechanism
Challenges of high injection pressure and low injection rate in low-permeability reservoirs which own vast macro or nano porous channels have drawn widespread attention because of their abundant re-serves.Although the wettability alteration can greatly enhance water injection,the increasing injection mechanism is barely reported.In this paper,we use a kind of silica nanofluid with an average size of 7 nm to study the wettability and permeability change of hydrophilic injection well.Silica nanoparticles with high surface activity could adsorb on the surface of porous channels and result in the transformation of wettability from hydrophilicity to hydrophobicity.The effective water permeability of core before and af-ter treatment that is measured versus water injection at different rates reveals that the effective water permeability is greatly enhanced with increasing the water injection rates.Compared with traditional sur-factant,the validity of injected nanofluid is significantly extended,exhibiting stable water permeability even after injecting water for 2 100 PV under a high flow rate.The increasing injection mechanisms are il-lustrated from two main aspects:Firstly,the critical point observed in the pressure-permeability curve corresponds to the wettability transformation of the pores from hydrophilic to hydrophobic,which can as-sociate the increased water injection with the hydrophobic capillary mechanism.The interfacial reactions between injected water and porous channels surface,including capillary pressure,adhesion work and injec-tion pressure are studied to explain the increasing injection mechanism.Secondly,the hydrophobic silica film on the core surface can effectively prevent the contact between water and channel surface from form-ing the carbonate scale in the micro and nano porous channels.Meanwhile,the expansion ratio of clay in the nanofluid is marked reduction and the effective porosity is also creasing from 18.3%to 23.1%.In all,the wettability alteration plays an important role in the increased water injection.We hope these findings could promote the application of silica nanofluid in enhanced oil recovery.
Silica nanofluid wettability increasing injection mechanism water-resisting layer critical re-sistance
Peisong Liu Liyong Niu Xiaohong Li Zhijun Zhang
Engineering Research Center for Nanomaterials,Henan University,Kaifeng,Henan,475004,China;Henan Wang Engineering Research Center for Nanomaterials,Henan University,Kaifeng,Henan,475004,China
国内会议
青岛
英文
52-63
2018-06-20（万方平台首次上网日期，不代表论文的发表时间）